vue.config.js failing calls to require() are now ignored

[mrozekma]

Version

4.3.0

Reproduction link

https://github.com/mrozekma/vue-cli-bug-demo

Environment info

Environment Info:

  System:
    OS: Linux 4.19 Debian GNU/Linux 9 (stretch) 9 (stretch)
    CPU: (4) x64 06/8e
  Binaries:
    Node: 12.10.0 - /usr/bin/node
    Yarn: 1.19.1 - /usr/bin/yarn
    npm: 6.10.3 - /usr/bin/npm
  Browsers:
    Chrome: Not Found
    Firefox: 68.7.0esr
  npmPackages:
    @vue/babel-helper-vue-jsx-merge-props:  1.0.0 
    @vue/babel-plugin-transform-vue-jsx:  1.1.2 
    @vue/babel-preset-app:  4.3.1 
    @vue/babel-preset-jsx:  1.1.2 
    @vue/babel-sugar-functional-vue:  1.1.2 
    @vue/babel-sugar-inject-h:  1.1.2 
    @vue/babel-sugar-v-model:  1.1.2 
    @vue/babel-sugar-v-on:  1.1.2 
    @vue/cli-overlay:  4.3.1 
    @vue/cli-plugin-babel: ^4.3.0 => 4.3.1 
    @vue/cli-plugin-router: ^4.3.0 => 4.3.1 
    @vue/cli-plugin-typescript: ^4.3.0 => 4.3.1 
    @vue/cli-plugin-vuex:  4.3.1 
    @vue/cli-service: ^4.3.0 => 4.3.1 
    @vue/cli-shared-utils:  4.3.1 
    @vue/component-compiler-utils:  3.1.2 
    @vue/preload-webpack-plugin:  1.1.1 
    @vue/web-component-wrapper:  1.2.0 
    typescript: ~3.8.3 => 3.8.3 
    vue: ^2.6.11 => 2.6.11 
    vue-hot-reload-api:  2.3.4 
    vue-loader:  15.9.2 
    vue-router: ^3.1.6 => 3.1.6 
    vue-style-loader:  4.1.2 
    vue-template-compiler: ^2.6.11 => 2.6.11 
    vue-template-es2015-compiler:  1.9.1 
  npmGlobalPackages:
    @vue/cli: 4.2.2

Steps to reproduce

Run yarn serve. It will load successfully. Then downgrade to @vue/cli-service@4.2.3 and yarn serve will correctly fail.

What is expected?

ERROR Error loading vue.config.js:
ERROR Error: Cannot find module 'bad-module'

What is actually happening?

Server loads successfully

---

Commit f1bdf73 simplified vue.config.js loading by not checking if the file exists, but instead just require()-ing it and catching the failure if it doesn't. However, this also suppresses cases where vue.config.js exists, but it in turn calls require() on something that doesn't exist, since all the exception handling code looks for is e.code === 'MODULE_NOT_FOUND'